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We have also broadened this chemistry to included magnesium-diene intermediates derived from isoprene, myrcene, and 2,3-dimethyl- 1,3-butadiene in addition to the 1 ,Zbis(methy1ene)cyclohexane complex. Table 1-5. Rcactions of diene-magnesium reagents with carboxylic esters. Formation of cyclopentenols. ~~ Entry l 3 o Diene = Ester Product Yielda) CH3COOEt 91 CH3(CH2)2COOEt 96 PhCOOEt 55 = a< CH3(CH2)2COOEt a) Fused bicyclic product was obtained under reflux. 59 74 16 I Rieke Metals: Highly Reactive Metal Powders Table 1-6.

It lacked thc rcactivity necessary to react with the majority of organic halidcs. When compared with other metals produccd by the Rieke method of metal activation, copper suffers from the disadvantage of sintering into larger particlcs, thereby reducing its reactivity. It was apparent that the main difficulty associated with the copper metal \intering was the cxceptionally long reduction time. Previous reports from our laboratory have shown a correlation between particle size and reactivity [71].

This includes geminal disubstituted alkenes. Table 1- 15 shows examples of reactions of organozincs with allylic halides mediated by CuCN . 2 LiBr. We also found it possible to make 2,3-disubstituted-l,3-butadiencsusing CuCN . LiRr and cross-coupling with 1,4-dichlor0-2-butyne. This reaction was very regiospecific, giving S N ~ products. ' Unfortunately, arylzinc compounds did not yield the S N ~product ' when reacted with 1,4-dichloro-2-butyne. However, when reacted with 1,4-ditosyloxy-2butyne, aryl and alkyl organozincs gave excellent yields of the Ss2' products.